Walk in to any gym these days and you'll see people training harder than they ever have before.

There's a schoolteacher cranking out hundreds of burpees, an accountant busting out a barbell complex and a tradie performing the circuit to end all circuits. Blame it on CrossFit, Instagram or the internet, everybody wants to be hardcore in the gym.

Yes, ultra-intense HIIT workouts are all the rage right now, but that doesn't mean you should be doing them every time you set foot in the gym, says sports scientist and strength and conditioning guru Brando Hasick.

"While the duration of your session may be shorter; the speed of your reps shouldn’t become quicker."

Tension is a good thing in the gym

As Hasick explains, if you're looking to add size and shape to your muscles, you'll need to utilise one of the oldest bodybuilding tricks in the book known as time under tension (also known as TUT).

TUT focuses not on the size of the weight you're using, but the tempo and speed at which you're using it. Essentially, the longer you have your muscles under considerable tension, the more prompted they are into growing larger to compensate.

"The best way to get strong, have toned muscles and ultimately low body fat, is to ensure that you are controlling the force production, to the correct muscle," says Hasick.

A simple test to try at home

To describe this concept to his clients, Hasick has them do a quick push-up test which you can try at home:

1. Find some spare space on the floor, and crank out five push-ups as quickly as you can. Think about how long that took you to complete – it should be somewhere between six and 10 seconds.

2. After a quick breather, jump back into your push up position but this time count to five every time you lower yourself down. Do the same set of five push-ups, and see how long it takes you.

If you've done the test correctly, the slower push ups should have been considerably harder, thanks to the greater amount of time your chest and triceps had under tension. Not only does this require extra strength, it also promotes a bigger response from your body, and burns more calories.

"When you learn to drive, you don’t start driving 100km per hour on your first day, so why do it in the weights room?" explains Hasick.

"By focusing on control rather than speed, it enables you to mentally focus on the mind-muscle connection to finely tune which muscles are activated."

You can still have a quick workout with slow movements

If you've only got a limited amount of time to spend in the gym – and let’s face it, who doesn't – that doesn’t mean you miss out on all benefits of incorporating TUT into your training.

As Hasick points out, it's more about the speed of your movements, not the speed of your workout itself.

Think about doing things like combing super-slow front squats with equally slow pull-ups – not only will you get through a mountain of work, you'll also have every stabiliser muscle in your body screaming out for relief in under two minutes.

"No matter what age, gender or size you are, you should always be dedicating a big chunk of your training towards 'slow strength', even if your main goal is to produce quick speed or power," recommends Hasick.

"Nothing good comes from trying to win the weights race."

Brando Hasick's "Short but slow" sample workout

If you've got just 10 minutes to spare, you can complete this gruelling workout that Hasick has designed himself incorporating all kinds of tortoise-speed exercise.

The workout is structured as a 10 minute EMOM (which means every-minute-on-the-minute). The quicker you complete the set, the more time inside the minute you have to rest. It's short, brutal and dangerously effective.

Minute 1: Do 6 – 8 reps of a barbell back squat with 60 percent of your 1 rep max (rm). Count to three as you're descending in the squat.

Minute 2: Once it hits 60 seconds on the clock, do 6 – 8 pull-ups, making sure to count to three as you lower yourself down (see video for reference).